Reed relay

ABSTRACT

The reed relay comprises a pair of fixed contact supports arranged at a regular spacing therebetween. A reed strip has a movable contact at a free end thereof and arranged so that the movable contact is positioned between the two fixed contact supports. A coil is wound around the reed strip, and a permanent magnet is disposed on one side of the movable contact. Since the permanent magnet is not positioned on the extension line of the reed strip, it is possible to readily inspect the contact conditions and the contact pressure without interruption due to the presence of the permanent magnet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a reed relay used forautomatically controlled various machines, equipment, systems, etc., andmore specifically to a reed ralay of such a type that a permanent magnetis provided therein and the switching action can be made according tothe direction that current is passed through an energizing coil incooperation with the built-in permanent magnet.

2. Description of the Prior Art

An example of the prior-art reed relays of this type has been disclosedin Japanese Patent Publication No. 58-49977. In this reed relay, thepermanent magnet is disposed on an assumed extension line of a reedstrip having a movable contact at its free end. Since the reed strip isplaced within a bobbin or a frame, the reed strip can be inspected onlyfrom the outside along the extension line of the reed strip. In theabove prior-art reed relay, however, since the permanent magnet isdisposed at the front of the movable reed contact (the free end) of thereed strip, this permanent magnet covers the movable reed contact, thusresulting in problems in that it is impossible to inspect or confirm thecontact pressure and the contact conditions of the movable reed contactduring or after reed relay assembling process. The above-mentioneddrawbacks cause the dispersion in reed relay characteristics or the lackof stability in reed relay switching operation.

SUMMARY OF THE INVENTION

With these problems in mind, therefore, it is the primary object of thepresent invention to provide a reed relay such that it is possible toreadily inspect or confirm the contact conditions and the contactpressure during or after assembling the reed relay elements in spite ofa relatively simple relay construction.

To achieve the above-mentioned object, the reed relay according to thepresent invention comprises a pair of fixed contact supports each havinga fixed contact and arranged at a regular spacing therebetween, a reedstrip having a movable contact at a free end thereof and arranged sothat the movable contact is positioned between a pair of the fixedcontact supports, a coil wound around the reed strip, and a permanentmagnet disposed on one side of the movable contact.

In the reed relay according to the present invention, since thepermanent magnet is disposed on one side of the movable contact of thereed strip, the front space of the reed strip, that is, the space alongthe extension line of the movable contact formed at the free end of thereed strip is perfectly open towards the outside. Accordingly, even whenor after the reed strip is inserted into a bobbin or a frame andtherefore the reed strip is surrounded by the bobbin, the worker caneasily inspect or confirm the contact conditions and the contactpressure of the movable contact of the reed against the fixed contact.Consequently, the worker can readily adjust the contact conditions andthe contact pressure in order to manufacture reed relays of uniformquality and stable switching operation. Additionally, there existsanother advantage such that is it possible to reduce the overall lengthof the reed relay by a dimension corresponding to permanent magnet inthe longitudinal direction of the reed relay, thus realizing a morecompact reed relay.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the reed relay according to the presentinvention will be more clearly appreciated from the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective exploded view showing all the elementsconstructing the reed relay according to the present invention;

FIG. 2 is a perspective view showing the positional relationship betweena reed strip, pair of fixed contact supports, and permanent magnet; and

FIG. 3 is a lateral cross-sectional view of the aasembled reed relay.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 to 3, the reed relay according to the presentinvention is composed of a base 10, a switching mechanism including areed strip 30 and a pair of fixed contact supports 40 and 50, a supportmember 20 for the switching mechanism, and a causing 60.

The base 10 is made of an approprite insulating material such as resinand formed with a rising wall 16 for supporting the support member 20along the outer periphery of the base 10. Near both the ends of one sideof the base 10, two coil terminal pins 11 and 12 are vertically disposedpassing through the base 10 and extending toward the inside and theoutside of the relay. Further, on the other opposite side of the base10, there are formed three vertical holes 13, 14 and 15 through whichthree connector pins (discribed later) are passed.

The reed strip 30 made of an elastic magnetic material has a movablereed contact 31 at the free end thereof. The surface of the movable reedcontact is treated or plated by a contact material such as platinumrhodium. The base end 32 of the reed strip 30 is fixed by welding, forinstance, to roughly the middle portion of a reed support 34perpendicular thereto. At one end of the reed support 34, a commonconnector pin 33 is formed integrally with and perpendicularly to thereed support 34.

The two fixed contact supports 40 and 50 are also made of a magneticmaterial. At one end of the fixed contact support 40, a connector pin 43is formed via a horizontally extending connecting member 44 integrallywith and perpendicularly to the fixed contact support 40. Similarly, atone end of the fixed contact support 50, another connector pin 53 isdirectly formed integrally with and perpendicularly to the fixed contactsupport 50. At roughly the middle on the mutually opposing surfaces ofthese two fixed contact supports 40 and 50, a make-side contact 41 and abreak-side contact 51 are mounted, respectively, so as to face to eachother.

The support member 20 includes a hollow bobbin 21 around the outercircumference of which a coil 29 is wound, and two flanges 22 and 23formed at both the ends of the bobbin 21 integrally therewith. Theflange 23 is formed with an opening 25 at the middle thereof. At theupper and lower positions in the opening 25 and on the side surface ofthe flange 23, there are formed grooves or recesses 26 for receiving thetwo fixed contact supports 40 and 50, respectively. Similarly, theflange 22 is formed with an opening (not shown) at the middle thereof.In the opening of the flange 22, there are formed similar grooves orrecesses 27 for receiving the reed support 34 for supporting the reedstrip 30 and the common connector pin 33. Further, on the other sidesurface of each flange 22 or 23, there is formed a vertical groove 28(shown in FIG. 3) into which the coil terminal pin 11 or 12 isengageably inserted, respectively.

The support member 20 is placed on the base 10. The reed strip 30 ispassed through the hollow portion of the bobbin 21 and is heldtherewithin at such a position that the movable contact 31 of the reedstrip 30 is positioned at the center of the opening 25 and also betweentwo fixed contact supports 40 and 50 located at the upper and lowerpositions in the opening 25 in the flange 23.

A permanent magnet 49 is fixed on the upper surface of the fixed contactsupport 50 near one end and at one side thereof at such a position as tocorrespond to one side of the movable reed contact 31. The width and thethickness, where necessary, of the fixed contact support 40 are formedgreater than those of the fixed contact support 50. The connector pins33, 43 and 53 are all inserted into the three holes 13, 14 and 15,respectively, formed vertically in one side of the base 10 in such a wayas to project toward the outside from the base 10. Both the ends of thecoil 29 are connected by soldering, for instance, to the top end of thecoil terminal pins 11 and 12, separately.

The casing 60 is made of a magnetic material, the inside surface ofwhich is coated by an insulating material. This casing 60 is assembledwith the base 10 so as to cover the support member 20, the reed strip30, the fixed contact supports 40 and 50, etc. all assembled on the base10.

Under the normal conditions, the movable contact 31 of the reed strip 30is attracted toward the break-side contact 51 mounted on the fixedcontact support 50 into contact therewith by a magnetic force generatedby the permanent magnet 49. When current is passed through the coil 29in a predetermined direction, however, the reed strip 30 is excited, sothat the movable reed contact 31 is urged toward the make-side contact41 mounted on the fixed contact support 40 into contact therewith awayfrom the break-side contact 51 by a repulsive force generated betweenthe movable reed contact 31 and the fixed break-side contact 51 andadditionally by an attractive force generated between the movable reedcontact 31 and the fixed make-side contact 41. The above-mentionedswitching operation of the reed strip 30, of course, allows theelectrical connection to be changed-over from the connection between theconnectior pins 33 and 53 to the connection between the connector pins33 and 43 or vice versa. Further, a coil current is supplied to the coil29 for energization through the two coil terminal pins 11 and 12.

As described above, only when current is passed through the coil 29 in apredetermined direction, the reed strip 30 is brought into contact withthe make-side contact 41, thus the operation of the reed relay beingachieved. Further, since the fixed contact support 40 having themake-side contact 41 is formed greater in size or dimensions than thefixed contact support 50 having the break-side contact 51, the magneticflux generated when the coil 29 is energized can easily flow through themagnetic path, as depicted by the dashed-lines in FIG. 2, thus resultingin a higher sensitivity in the relay switching operation.

By the way, the position of the movable contact 31 of the reed strip 30,the contacting conditions and the contact pressure between the movablecontact 31 and the fixed make-side and break-side contacts 41 and 51should be inspected or checked during the assembling process of the reedrelay. In more detail, the above inspection should be made after thefollowing steps: the reed strip 30 is inserted into the bobbin 21 of thesupport member 20; the reed support 34 for the reed strip 30 is engagedwith the groove 27 of the flange 22; on the other hand, the two fixedcontact supports 40 and 50 are engaged with the grooves 26 of the flange23; the support member 20 is placed on the base 10; each connector pin33, 43 or 53 is inserted into each hole 13, 14 and 15 formed in the base10, separately; and further the coil terminal pins 11 and 12 are engagedwith the grooves 28. That is, the above inspection should be made beforeputting the casing 60 on the assembled reed relay mounted on the base10.

To inspect the contact pressure, for instance, a sensor of a tensionmeter is inserted under the reed strip 30, especially under the movablecontact 31 through the opening 25 in the flange 23 of the support member20, and a force required to release the contacting condition in whichthe movable reed contact 31 is in contact with the fixed break-sidecontact 51 is measured by pushing the reed strip 30 in the upwarddirection with the tension meter sensor. In the above-mentionedinspection process, since the permanent magnet 49 is positioned not onthe extension line of the reed strip 30 but on the side of the movablecontact 31 of the reed strip 30, it is possible to achieve theabove-mentioned inspection operation easily and accurately. In case theposition and the conditions of the reed strip 30 is found to beunacceptable, the reed strip 30 is adjusted by twisting or bending theportion of the reed support 34 at which the base end 32 of the reedstrip 30 is fixed thereto by welding, for instance.

Upon completion of the adjustment as described above, both the ends ofthe coils 29 are soldered to the coil terminal pins 11 and 12,separately; the casing 60 is put on the base 10 for covering the relayassembly; a sealing material 70 is filled up on the outer surface of thebase 10, as shown in FIG. 3, in order to fix the casing 60 and therespective connector pins 33, 43 and 53 to the base 10.

What is claimed is:
 1. A reed relay comprising:(a) a pair of fixedcontact supports mounted at a first end of said relay each having afixed contact thereon and arranged at a regular spacing therebetween;(b) a reed strip having a fixed end mounted at a second end of saidrelay being opposed to said first end and a movable contact at a freeend thereof and arranged so that said movable contact is positionedbetween said pair of fixed contacts, said movable contact also having apair of sides; (c) a coil wound around said reed strip; and (d) apermanent magnet disposed in contact with one of said fixed contactsupports and on one of said sides of the movable contact of said reedstrip and being spaced apart therefrom to allow an unobstructed viewingspace to remain at the first end of the relay, allowing viewing of thefree end of said reed strip.
 2. The reed relay as set forth in claim 1,wherein one of said fixed contact supports is provided with a make-sidefixed contact and the other thereof is provided with a break-side fixedcontact, said fixed contact support provided with said make-side fixedcontact is greater in size than that provided with said break-side fixedcontact.
 3. The reed relay as set forth in claim 2, wherein saidpermanent magnet is fixed to said fixed contact support provided withsaid break-side fixed contact.
 4. A reed relay comprising:(a) a supportmember including a hollow bobbin and first and second flanges formed atboth ends of said hollow bobbin, each of said flanges being formed withan opening at a middle thereof; (b) a pair of fixed contact supportsfixed at upper and lower positions of the opening formed in the firstflange of said support member; (c) a reed strip having a fixed end fixedto the second flange of said support member and a free end extendingthrough the hollow bobbin to the opening formed in the first flange, ata front portion of the relay the free end being positioned between apair of said fixed contact supports so as to serve as a movable reedcontact, said movable reed contact having a pair of sides; (d) a coilwound around an outer circumference of the hollow bobbin of said supportmember; (e) a permanent magnet disposed in contact with one of saidfixed contact supports and on one of said sides of the movable reedcontact and being spaced apart therefrom to allow an unobstructedviewing space to remain in the front portion, allowing viewing of thefree end of said reed strip; (f) a base for receiving said supportmember; and (g) a casing for covering said base and said support member.5. The reed relay as set forth in claim 4, wherein said permanent magnetis fixed to one of said fixed contact supports.
 6. The reed relay as setforth in claim 4, wherein said casing is made of a magnetic material.